4 DEPARTMENT BULLETIN 975, U. S. DEPT. OF AGRICULTURE. 
pared with that in turnips shows that lettuce is a better source of 
iron. By comparing the lines in the different charts in this way, a 
person can see what the various foods can be depended on to supply. 
Not aways, however, is the body able to utilize equally well the 
nutritive elements present in different kinds of food. As will be 
discussed later, care must be used to select foods not only from a 
quantitative standpoint, but also with reference to digestibility, cost, 
dietary suitability, and the relative values of the types of protein, 
fat, carbohydrate, calcium, phosphorus, and iron which they may 
contain. 1 
FOOD VALUES NOT SHOWN ON THE CHARTS. 
In publishing these charts, which deal with food factors that can 
be measured by weight, there is no intention of undervaluing those 
other factors that can not be so measured, namely, the vitamines. 
Though the quantities of vitamines in different food materials have 
not yet been determined and the comparative vit amine values can 
not yet be satisfactorily expressed by lines or figures, general state- 
ments can be made in many cases and are given in connection with 
the charts. 
Scientists now recognize at least three vitamines which, until more 
satisfactory names are agreed upon, may be called A, B, and C. Vita- 
mine A is believed to be necessary for normal growth and develop- 
ment. It is sometimes known as fat-soluble A, because it is found 
associated with fat, and sometimes as the antirachitic vitamine, be- 
cause when it is absent from the diet rachitis, or rickets, is likely to 
occur. It is found in milk, egg yolk, green-leaf vegetables, fats sur- 
rounding the vital organs of animals, and to a less extent in meat, 
and perhaps in certain fruits. Vitamine B is also believed to be 
necessary for general well-being. It is sometimes called water-solu- 
ble B, and sometimes the antineuritic vitamine. because lack of it 
may bring on polyneuritis, or beriberi. It is present in nearly all 
food materials except those that have been artifically purified, such as 
white sugar, white flour, and cornstarch, and most table oils. Vita- 
mine C is sometimes known as water-soluble C, or as the antiscorbutic 
vitamine. because lack of it may be a cause of scurvy, or scorbute. 
It is found especially in certain fruits and vegetables, among them 
tomatoes, carrots, oranges, lemons, and grapefruit. It also occurs 
in fresh milk and probably in meat. Its efficacy in some foods seems 
to be easily destroyed by heat and sometimes by drying or even by 
ordinary storage, so that raw, fresh foods are in general the more 
reliable sources of it. 
1 The charts are based on average analyses published in Chemistry of Food and Nutri- 
tion, by H. C. Sherman, New York, 191S, and on additional data determined by Lucy H. 
Gillett at Columbia University. 
